/*
 * Copyright 2016 requery.io
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package io.requery;

import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;

import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

/**
 * Indicates the owning side of a Many-to-Many relationship, and defines the junction
 * (cross reference) table to use to map the relationship.
 *
 * @author Nikhil Purushe
 */
@Documented
@Target({FIELD, METHOD})
@Retention(RUNTIME)
public @interface JunctionTable {

    /**
     * @return name of the table. Defaults to the entity tables appended with an underscore, e.g.
     * for two tables A and B in a relationship the junction table name would be A_B.
     */
    String name() default "";

    /**
     * @return optional column data for the table definition, if empty defaults to 2 foreign key
     * column entries named {table}Id.
     */
    Column[] columns() default {};

    /**
     * @return the class with the junction table definition, this class must be suitable for
     * joining the two types between the {@link ManyToMany} relationship. If not specified
     * the processor will generate a junction type class.
     */
    Class<?> type() default void.class;
}
